The present invention relates generally to the manufacture of electrical machines, such as electric motors or generators. More particularly, the present invention relates to a device and method for inspecting core laminations of an electrical machine.
Electrical machines produced according to mass production techniques will often utilize a plurality of core laminations which have been stacked and welded together. For example, both the stator and rotor of AC induction motors are typically produced in this manner. The individual laminations are frequently produced from larger sheets by industrial punch presses. In the case of stator laminations, the punch press will often form a series of slots about the lamination's inner diameter. After a plurality of these laminations are stacked and welded, the slots are stuffed with wire bundles through which the driving current will flow.
Typically, the stator laminations further include various timing slots about their outer diameter. For various reasons, the timing slots are often formed in the lamination prior to the stage in which the inner diameter slots are produced. For manufacturing consistency, however, it is desirable that a predetermined orientation be maintained between the wireway slots on the lamination's inner diameter and the outer diameter timing slots. It is also desirable that this predetermined orientation be maintained from one lamination to the next.
The predetermined orientation between the wireway slots and the timing slots is ideally fixed when the punch press is set up. In the past, however, it has generally been necessary to adjust the punch press by relatively crude trial and error techniques. In other words, sample laminations are produced and then inspected for conformance with final specifications. If the predetermined orientation has not been achieved, the punch press is adjusted based on the skill of the operator in an effort to reduce such error. Subsequent adjustments are made iteratively as additional laminations are produced until the predetermined orientation has been achieved.